The present invention is directed to a method of shifting a bicycle transmission and, more particularly, to a method of shifting a bicycle transmission using predicted (virtual) values.
As with automobiles, automatic shifting is also desired in bicycles. Automatic shifts are controlled by a computer on the basis of electrical signals representative of such values as chassis acceleration, velocity, crank spindle torque, and so on. The sensing of velocity is known from numerous publications. For example, in U.S. Pat. No. 4,071,892 the velocity is calculated by sensing the period of the wheel revolution with a moving-side sensor which is attached to the wheel spokes and a stationary-side sensor that is fixed on the bicycle chassis. Performing automatic shifting on the basis of the velocity thus sensed is also known from numerous publications, such as U.S. Pat. No. 4,071,892 and Japanese Laid-Open Patent Application 8-113182. A shift that is performed electrically does not have to be an automatic shift, and may also be performed as desired by the rider.
However, even when shifting is performed as desired by the rider, it is usually desirable to shift the transmission when there will be a smooth transition from one gear to another and/or to perform the actual shift during deceleration, when the drive system of the shift mechanism is easier to operate. No such shift capability is known, however. If such a method is to be implemented, then from the standpoints of cost, maintenance inspection, light weight, and so on, as few sensors as possible should be used.